TABLE 5

The ratio of the log K_B value for CGP12177 (as an antagonist of cimaterol) and log EC₅₀ value for CGP12177 for responses seen at the β₂-WT and β₂-TM chimeric receptors (data taken from Table 4)

Ratios of the affinity for antagonists at the two conformations are also given (i.e., log K_B for antagonism of cimaterol/log K_B for antagonism of CGP12177). This table examines the ratio of the affinities of ligands at the β₂-adrenoceptor and thus allows for differences in absolute affinity. ICI118551 has lower affinity at the β₂-TM4 receptor (Table 4), but this occurred both in the presence of cimaterol and CGP12177; thus, the ratio is similar to that at the other receptors. There is no large consistent change with any of the receptors.

	Ratio of Log K_B CGP12177/Log EC₅₀ CGP12177	Ratio of Log K_B (Cimaterol as Agonist)/Log K_B (CGP12177 as Agonist)
	Ratio of Log K_B CGP12177/Log EC₅₀ CGP12177	CGP20712A	Bisoprolol	ICI118551	Propranolol
β₂-WT	0.65	−0.09	0.25	0.25	0.63
β₂-TM1	0.26	0.46	0.19	0.23	0.49
β₂-TM2	0.81	0.41	0.25	0.27	0.55
β₂-TM3	0.81	0.36	0.52	0.24	0.86
β₂-TM4	0.63	0.04	0.41	0.45	1.00
β₂-TM5	0.51	0.16	0.06	0.19	0.71
β₂-TM6	0.78	−0.26	0.33	0.47	0.41
β₂-TM7	0.01	0.35	0.47	0.09	0.28